The invention relates to a dispenser for discharging flowable media with a preferably manually operated pump. Such pumps are intended for liquids, pastes, foams, etc. and are used for their dosing, spraying or other discharging processes. The pumps used are usually thrust piston pumps, which are operated by means of a hollow piston rod and a pushbutton or trigger mounted thereon and which simultaneously carries the discharge opening, e.g. a spraying nozzle.
When operating such dispensers it is always a problem to make the discharge process independent of the individual operation by the user in order to e.g. produce a uniform dosing and in particular, in the case of spraying devices, a uniform spray pattern.
Therefore dispensers have been developed which operate in such a way that when operated by the user they firstly tension a spring, followed by a spring-operated discharge process. Mention is e.g. made in this connection of U.S. Pat. No. 6,145,710 A, which on depressing the discharge nipple a piston connected thereto in a larger diameter cylinder displaces counter to a spring tension a piston running in a smaller diameter cylinder connected thereto. After opening the delivery valve by releasing a fixed head, the liquid can be discharged under the tension of a spring acting on the smaller piston.